Replace internal GLFW bindings with pyGLFW

[romanroibu]

This PR replaces the internal glfw.py bindings with external pyGLFW.

Install the external bindings using pip:

pip install glfw

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ClickUp Task

[pfaion]

@romanroibu can you add pip install glfw to https://github.com/pupil-labs/pupil/blob/master/.travis/run_tests.sh
This should fix the Travis errors hopefully.
Makes sense to add this on this PR I think.

[romanroibu]

@pfaion Thanks for reminding me 👍🏻 I added your suggestion, and also updated the dependency documentation.

The only thing I haven't touched is the bundle deployment scripts, but there seem to be useful functions to get the path(s) to the library files. @papr Please let me know if you want me to try to update these; I don't have a lot of experience with PyInstaller, but can take a stab at it.

[papr]

Bundling works. Only issue: There was a case where the clipboard could not be accessed on Windows. Might be a race condition.

[papr]

pyGLFW 2.0.0 was just released. Most notably, the default error reporting changed from raise to warn (reasoning).

[pfaion]

@romanroibu is there not a better version to change ERROR_REPORTING than to change this after every import? This seems somehow very verbose and easy to forget.

[romanroibu]

@pfaion for most use-cases it's probably enough to change the ERROR_REPORTING after the imports in the launchables, since the rest of the code runs in the context of a launchable process. However, I'm not sure if no other process is calling any glfw method, so I just added this statement after each import for safety.

I couldn't think of a better way to globally change the error reporting behaviour.